Memory CD45RO+CD45RA- CD4+T cells are associated with a lower induction of FOXP3 by (transforming growth factor beta) TGFβ and retinoic acid (RA) in systemic lupus erythematosus (SLE) patients. (a) Treg expansion by RA in the presence of 1 ug/ml of TGFβ was negatively correlated with the percentage of memory CD4+ T cells in the peripheral blood mononuclear cells (PBMCs) of SLE patients but not healthy controls (HCs). (b) Treg expansion by the combination of RA and 1 ug/ml of TGFβ over the absence of both RA and TGFβ was negatively correlated with the percentage of memory CD4+ T cells in the PBMCs of SLE patients but not HCs. HCs are represented by white symbols and dashed linear regression lines; SLE patients are represented by grey symbols and plain linear regression lines. The P-values for Spearman correlation tests and the R2 values are shown for the patient and HC cohorts. Ns, non-significant.